I did weight watchers years ago (wasn't overweight - just wanted to trim down) and it worked great but like everything, you have to maintain. I'm now almost 54 and have never been as heavy as I am now. Last fall my doctor told me to lose 10 pounds - after that I gained five
but I'm back on track now and have lost the 5 plus 6 so 4 pounds to go - however, I want to lose another 10 besides.
A friend of mine (that can think of any excuse why her current diet plan doesn't work) said the problem with weight watchers was that it didn't teach you proper eating. You could in theory get all you daily points from fat - I guess it is possible - though to me unlikely.
If you join weight watchers for say 3 months and recorded all you ate on FitDay you would have your points broken down to calories and if you averaged out how many calories kept you within those points, you would know what you should eat calorie wise. Some people need the support of meetings - if so then do what works for you - it is better then buying the expensive pre-packaged diet plans that don't teach you anything!